System of distribution.



F. W. HARRIS.

SYSTEM OF DISTRIBUTION.

APPLICATIONFILED MAR.13. 1911.

1,173,569. Patented Feb. 29,1916.-

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STATES PATENT OFFICE.

FOBILW. HARRIS, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOB TO WESTINGHOUSEELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

SYSTEM OF DISTRIBUTION.

new and useful Improvement in Systems of Distribution, of which thefollowing is a specification.

My invention relates to systems of electrical, distribution, andparticularly to such systems as are adapted to supply energy from acommon distributing bus-bar to a plurality of feeder circuits.

The object ofmy invention is to provide a system of the above-indicatedcharacter that shall be simple in arrangement and oporation, and shallembody a circuit interrupter in each feeder circuit, an auxiliarycircuit interrupter of relatively large capacity connected in seriesbetween the distributing bus-bar and the source of energy, and automaticmeans for selectively opening said feeder interrupter or auxiliaryinterrupters in accordance with predetermined overload conditions.

In power stations of large capacity, it is the usual practice to provideeach feeder circuit with an individual interrupter which is required tohandle all overloads, irrespec tive of the degree thereof. Hence, thefeeder interrupters which are designed and constructed to operate onmoderate overloads are required to interrupt the circuits underparticularly excessive demands and short circuits. It follows that suchinterrupters are subjected to very severe operating conditions and arefrequently badly damaged or completely destroyed when opening abnormalamounts of power for which they arenot designed. The cost of the repairand maintenanceof such apparatus is great and it is to reduce suchexpense that my invention is intended.

According to my present invention, I provide each feeder circuit with anindividual circuit interrupter of such capacity as to successfullyhandle moderate overloads, while I employ an auxiliary circuitinterrupter of relatively large capacity which I connect in seriesbetween the distributing bus-bar and the'source of energy, saidinterrupter being adapted to interrupt the circuit under conditions ofparticularly excessive overloads or short circuits.

In order to relieve the feeder circuit Specification of Letters Patent.

Application filed March 13, 1911.

Patented Feb. 29, 1916.

Serial No. 614,252.

breakers from handling overloads in excess of their capacity, I providesuitable series transformers, relays and switchi g devices whereby Iselectively open the, fe der interrupters or the auxiliary interrupterin accordance with the degree of overload. i

The single figure of the accompanying drawing is a diagrammatic View ofa system pf distribution which embodies my inven- Referring to thedrawing in detail, a plurahty of generators 1, having ground connectionsat G, and field magnet windings 2, are connected to a common generatorbusbar from which energy is delivered to a distributing bus-bar 4,through an auxiliary interrupter 5 and the primary winding of a seriestransformer 6, the secondary winding of whlch 15 adapted to energize arelay 7 in accordance with predetermined circuit conditions. The relay 7is provided with a switch member 8 and upper and lower contact terminals9 and 10, respectively.

The distributing bus-bar 4: is connected to a plurality of feedercircuits 11, 12 and 13, through interrupters 14, 15 and 16 and throughthe primary windings of series transformers 17, 18 and 19. The secondarywinding of each of the series transformers 17, 18 and 19 is adapted toenergize a primary relay 20 which carries a switch member 21 to engagecontact terminals 22.

The circuit interrupters 5, 14, 15 and 16 are of like constructiomexceptthat the interrupters 14, 15 and 16 are of much lighter construction andare severally provided -with auxiliary switch members 23 and cooperatingcontact terminals 24. Each interrupter comprises a bridging contactmember 25, coiiperating stationary contact members 26, an operatingmechanism 27 and a trip coil 28, and may be adjusted to openautomatically under any desired overload for which it is designed. Theultimate breaking capacity of the auxiliary interrupter 5 is sufficientto permit the interrupter to successfully open the most severe shortcircuits upon the system, while the capacity of the feeder interruptersis only suflicient to accommodate moderate over loads. The feederinterrupters are intended to be adjusted to handle the usual overloadswhile the auxiliary interrupter 5 is adjusted to open under all demandswhich exceed the amount for which the feeder interrupters are set. Itshould be understood that these interrupters form no part of myinvention, except as they perform a necessary function in the operationof the system, and, hence, any other suitable devices for accompllshingthe same purpose may be employed.

Cooperating with each primary relay 20, is a secondary relay which isprovided with a holding winding 31, a closing winding 32, a switchmember 33 and cooperating contact terminals 34. Each holding winding 31is so connected in circuit that it is energized whenever the feedercircuit interrupter with which it is associated is closed, although notsufficiently energized to raise the core 30, while the closing coil 32is dependent for energization upon the action'of the primary relay 20,and when so energized, is adapted to actuate the core 30.

The circuit connections and mode of operation of the system is asfollows: Assuming the circuit connections, switching devices, etc., tooccupy the positions shown in the drawing and that a moderate overloadexists upon the feeder circuit 11, energy is immediately supplied fromthe distributing bus-bar 4, through the primary winding of the seriestransformer 1?, to the feeder circuit. It is evident that, if thecurrent traversing the secondary winding of the series transformer 17exceeds the predetermined amount for which the relay is adjusted, saidrelay is energizedand causes the switch member 21 to engage itscooperating contact terminals 22, thereby completing a circuit from thepositive side of a battery 35, or other suitable source of energy,through a conductor 36, conductor 37, conductor 38, switch members 21and 22, conductor 39, closing coil 32, conductor 40, and conductor 41 tothe negative side of the battery. Thus, the closing coil 32 of thesecondary relay 30 is suiliciently energized to raise the switch member33 into engagement with the contact terminals 34 in which position it isheld by the holding coil 31.

A circuit is then completed from the positive side of the battery 35,through conductor 36, conductor 37, conductor 42, trip coil 28,conductor 43, switch members 33 and 34, conductor 44, conductor 45,switch members 8 and 10, conductor 46, and conductor41 to the negativeside of the battery 35. Upon the completion of the circuit just traced,energy is supplied to the trip coil 28 of the circuit interrupter 14 andsaid interrupter is opened in the usual manner, thereby disconnectingthe feeder circuit 11 from the rest of the system. As soon as theinterrupter 14 is opened, the current in series transformer 17 falls tozero and the switch member 21 associated with the primary relay 20 isdropped into its open position, thereby opening the circuit through theclosing coil 32 of the secondary 'cuit through the holding coil- 31 ofthe secondary relay 30 is interrupted, thus allowing the switch member33 to fall to its initial open position.

It is seen from the foregoing description that each of the feedercircuits may be selectively disconnected from the system by means of itsassociated feeder circuit interrupter under conditions of ordinaryoverload for which it is adjusted.

Assuming that an excessive overload or severe sl'ioi't-circuit existsupon the feeder circuit 11, said overload being in excess of the valuefor which the auxiliary circuit interrupter 5 is adjusted, the operationof the system is as follows: Upon the first rush of current through theseries transformers 6 and 17, the relays 7 and 20, respectively, areenergized simultaneously. The switch member 3 is drawn away from itslower contact terminals 10 and into contact with its upper contactterminals 9, tocomplete a circuit from the positive side of the battery35, through conductor 47, trip coil 28 of the auxiliary interrupter 5,conductor 48, switch members 8 and 9 and conductors 49, 46 and 41 to thenegative side of the battery. Energy is thereby supplied tdthe trip coil28 and the auxiliary circuit interrupter 5 is caused. to open and thusinterrupt the abnormal overload.

it has already been pointed out that the primary relay 20 is energizedconcurrently with the relay 7. Its switch member 21 is thereby raisedinto contact with contact terminals 22 to establish a circuit throughthe closing coil 32 of the secondary relay 30, in the mannerhereinbefore described. When the closing coil 32 is energized, switchmember 33 is caused to engage its contact terminals 34, as already setforth and is held in engagement by holding coil 31 as long as theinterrupter 14 is closed. However, inasmuch as the time consumed inoperating the two relays 20 and 30 is in excess of that required toeifect the operation of the single relay 7, it is evident that theswitch member 8 of the relay 7 is disengaged from its lower contactterminals 10 at the time when the switch member 33 of the secondaryrelay 30 makes contact with its contact terminals 34. ence, no circuitis established through the trip coil 28 of the feeder interrupter 14 andthe interrupter 14 is not opened until the cessation of the currentthrough the series transformer 6, by reason of the opening of theauxiliary interrupter 5, allows the relay 7 to drop its associatedswitch member 8 into contact with the lower contact terminals 10. Assoon as this cobperative engagement is efi'ected, energy is supplied tothe trip coil 28 of the feeder 36, conductor interrupter 14, through thecircuit hereinbefore traced. The interrupter 14 is thereby opened todisconnect the feeder circuit 11 fromthe system subsequently to theinitial interruption of the main circuit through the agency of theauxiliary circuit interrupter 5. It is evident then, thatthe feederinterrupter .14 is protected from opening an overload in excess of thatfor which it is adjusted and designed.

When the interrupter 14 is opened, energy is cut off from the holdingcoil 31 of the secondary relay 30 by reason of the disengagement of theswitch member 23 from its cooperating contact terminals 24. Thesecondary relay 30 is thereby deenergized, it being understood that theclosing coil 32 thereofwas deenergized through the agency of the primaryrelay when the current was cut off fromthe seriestransformer 7 by reasonof the opening of the interrupter 5. Hence, the switch member 33 isdisengaged from its contactterminals 34 and 'the supply of energy to thetrip coil 28 of the interrupter 14 is discontinued. The auxiliaryinterrupter-5 may then be closed and the normal operation of the systemresumed, except on the feeder 11 which sustained the overload and whichremains segregated from the distributing bus-bar 4 by reason of the openposition of the feeder interrupter 14. Thus, the defective feeder isindicated by the position of its own feeder interrupter.

Although Ihave' described the operation of the system in connection withan overload upon a single and a particular feeder circuit, it isevident, since all of the feeder trip coil circuits are interlocked withthe lower contact terminals 10 of the relay 7, that the system willoperate in a similar manner if a' plurality of feeder circuits areoverloaded or if any other particular feeder circuit is similarlyaffected.

In certain classes of power systems, it may be found expedient to somodify and rearrange the system hereinbefore set forth in detail thateach feeder circuitshall be provided with a plurality ofseries-connected interrupters of different capacities,

which may be selectively operated in a man ner similar to thatdescribed, such modifications in the arrangement of-circuits andauxiliary devices being within the province of those skilled in the art.I have shown and described the system in connection with single-phase ora direct-current distribution, but it will be readily understood thatpolyphase systems may be conveniently arranged to embody my inventionwithout exceeding the spirit and scope thereof.

I claim as my invention:

1. Thecombination with a source of energy, a plurality of feedercircuits, a circuit interrupter in each feeder circuit, and a circuitinterrupter of relatively large capacity between said source and saidfeeder interrupters, of means for opening said large capacityinterrupter under excessive overloads and subsequently selectivelyopening the overloaded feeder circuit interrupters and for opening theoverloaded feeder said large-capacity breaker under totalover loads inexcess of a predetermined amount and for subsequently opening thecircuit breakers associated with the overloaded feeders, and forselectively opening the breakers associated with the overloaded feederswhen the total overload is less than a predetermined amount. I

3. The combination with a source of energy, a plurality of feeder,circuits, a circuit breaker for each feeder circuit, and a relativelylarge-capacity circuit breaker connected in series between said sourceand said feeder breakers, of electro-responslve means for opening saidlarge capacity breaker under predetermined overload conditions and forsubsequently selectively opening the overloaded feeder breakers.

4. A distributing system comprising a source ofenergy, anda plurality offeeder circuits, a plurality of feeder circuit breakers,- an auxiliarycircuit breaker 'in series between said source and said feeder breakers,a main relay dependent upon thecurrent through said auxiliary breakerfor tripping said-breaker, a primary relay associated with each feedercircuit and dependent upon the current therein, and a secondary relayforeach feeder circuit and dependent upon the operation of said main relayand said associated rimary relay for tripping said feeder brea er.

5. A distributing system comprising a source of energy, a plurality *offeeders,a circuit breaker for each feeder, an auxiliary circuit breakerin series between said circuit breaker and said source, two cooperatmgrelays associated with each feeder breaker for tripping said feederbreaker, a holding coil and a closing coil for one of said relays, saidholding coil being normally energized, and a single relay associatedwith said auxiliary circuit breaker for tripping said breaker underpredetermined load conditions, said relay being interlocked with thetrip coil of each feeder circuit breaker.

6. A distributing system .comprising a source of energy, a plurality offeeder circuits, a plurality of feeder circuit breakers, an auxiliarycircuit breaker connected between said source and said feeder breakers,electro-responsive means for opening said feeder breakers underpredetermined load conditions, electro-responsive means for opening saidauxiliary breaker independent of said feeder breakers under otherpredetermined load conditions, and means for precluding the prioroperation of said feeder breakers under said last predetermined loadconditions. In testimony whereof, I have hereunto subscribed my namethis 7th day of March, 1911.

FORD W. HARRIS.

Witnesses J. L. EDWARDS, B. B. HINEs.

